Power driven case shift mechanism for typewriting machine



Jan. 11, 1966 J. w. MEINHERZ POWER DRIVEN CASE SHIFT MECHANISM FOR TYPEWRITING MACHINE 2 Sheets-Sheet 1 Filed Aug. 31, 1962 INVENTOR JOAC'H/M V. ME/A/f/EIQZ BY flv ATTORNEY Jan. 11, 1966 J. w. MEINHERZ 3,228,511

POWER DRIVEN CASE SHIFT MECHANISM FOR TYPEWRITING MACHINE Filed Aug. 51, 1962 2 Sheets-Sheet 2 INVENTOR JOA CHI/7 PV- ME/NHERZ ATTORNEY United States Patent M 3,228,511 POWER DRIVEN CASE SHIFT MECHANISM FOR TYPEWRITING MACHINE Joachim Wilhelm Meinherz, Paderborn, Germany, assignor, by mesne assignments, to Societe de Mecanographie Japy, Paris, France Filed Aug. 31, 1962, Ser. No. 220,715 Claims priority, application Germany, Sept. 5, 1961, A 38,251 4 Claims. (Cl. 19774) The invention relates to an arrangement for shifting from small to capital letters in power-operated typewriters or similar business machines having a continually rotating driving roller, a shiftable type-lever segment and a single revolution clutch controlled by the switchover or case shift key which temporarily connects the driving roller with an eccentric, producing the case shift motion.

In some devices or arrangements of this kind already known the type-lever segment in compulsorily led via intermediate members by the eccentric over the entire case shift path into each of the terminal or final positions. The two final positions of the segment corresponding to the normal position and the shift-over position are limited by adjustable stops. Due to the form-locking connection of the drive the up and down stroke positions of the eccentric must exactly coincide with the limit stops. To achieve this an extreme exactness in manufacturing of the parts of the eccentric drive and of the adjusting devices to vary the stroke are required.

In order to avoid this disadvantage it has already been proposed to locate the eccentric in a hole of a drive lever connected to the segment, said hole being elongated in the same direction as the shifting movement of the segment, with the segment being held in its final positions by a tumbler spring arrangement. This, however, permits a high speed of the segment in the last part of the shifting motion because it is free to be urged to its limit position by the tumbler spring although the eccentric driven parts may have slowed down Therefrom shocks result to the segment, the elimination of which would require an airbrake to dampen the shocks producing movementsof the segment.

It is the object of this invention to develop a simple eccentric drive for the segment case shifting which permits an easy adjustment of the segment to its final positions, which avoids shocks in the segment, provides a nearly noise-free operation and only small wear and tear even at an extended operation. To meet this requirement the eccentric is provided with recesses corresponding with the up and down stroke positions which, with the corresponding recesses in an eye which surrounds the eccentric and is located in a connecting or shift plate, cooperate in such a way that a clearance exists between the eye and the eccentric in the vicinity of their recesses only when the segment is close to either end of its travel. This clearance provides only a normal backlash between the respective parts. Said recesses are arranged in such a way that the connecting plate will be disengaged from the eccentric shortly before .the segment reaches the end of either its up or down positions. The recesses may consist of steps which connect adjacent circumferential arcs which are offset relative to each other and makeup the periphery of the eccentric.

Such an arrangement possesses the advantage that the segment will be braked at the end of each shifting motion by the eccentric itself, but just shortly before the segment reaches either of its final positions and its speed is almost down to zero, the eccentric will have rotated to a position relative to the eye where a clearance begins to develop between the eccentric and the surrounding eye. A separate air-brake is, therefore,-not required. In addition,

3,228,511 Patented Jan. 11, 1966 a rotary acceleration is applied to a clutching pawl simultaneously with the occurrence of the disengagement between the eccentric and the eye so that this acceleration is fully effective to release the pawl from its clutching-engagement with an associated ratchet wheel which is driven by the drive roller. The force required for this acceleration may be essentially less than in known arrangements. It is not necessary, according to the present invention, to precisely correlate the rotary positions of the eccentric with the up and down limit positions of the segment because of the clearance which comes into existence between the eccentric and its surrounding eye at these limit positions.

Another feature of the present invention is that the clutching pawl is acted upon by an arc-shaped blade spring which urges the pawl into clutching engagement with a ratchet wheel which is driven by the drive roller. The aforementioned acceleration which is applied to the pawl, when the eccentric and eye become disengaged, acts to disengage the pawl from the ratchet-wheel and this disengaging motion is dampened by the blade spring.

Further features of the invention may be gathered from the claims. A reference example of the invention will more closely be explained with the aid of drawings.

FIG. 1 shows in lateral view a shifting device according to the invention,

FIG. 2 shows a cross-section according to line AA in FIG. 1,

FIG. 3 shows a cross-section according to line BB in FIG. 2, and

FIG, 4 shows another operating position pertaining to FIG. 3.

A type-bar segment 1 carries in usual fashion the typebars of the typewriter. The segment 1 is carried in a ballprism guide 2 While it is also pivotally connected to one leg of an L-shaped lever 4, which in turn is pivotally journalled in stationary axle 3. The other leg of the lever 4 is connected to a connecting or shift plate 6 which comprises a generally circular eye 19, which in turn surrounds or embraces an eccentric plate 5. Eccentric 5 is eccentrically journalled for rotation relative to axle 15. It will be seen, therefore, that rotation of eccentric 5 about axle 15 will cause a generally sidewise oscillatory movement in plate 6 which in turn will pivot lever 4 about axle 3 in respective clockwise and counter-clockwise directions, and this in turn will move segment 1, respectively, down and up. It is seen, therefore, that the plate 6 performs its shifting motion when it is moved generally sidewise by the eccentric 5.

The up and down movement of segment 1 is limited by stop means which comprise a stud 7 fixedly attached to the typewriter frame. Adjustably axially spaced apart on said stud are stop nuts 9 and 10. Lock nuts 8 are used to assure that the stop nut remain in place. The segment 1 comprises an abutment arm 17 extending transversely to the up and down direction of movement. This arm 17 extends around the stud 7 and between the respective stop nuts 9 and 10. Damping washers 11, 12 are located on either side of the arm '17 and on the stud 7 and act as cushions to soften the impact of the arm 17 at it abuts against either of the stop nuts.

A tumbler spring 13 acts against the segment 1 to alternately urge it either to its up position or to its down position depending upon which position the segment is in at the moment.

The eccentric is rotatably journalled on the hub of a ratchet wheel 14 (FIG. 2) which is secured to the axle 15 of the driving roller 16 permanently driven by an electric motor (not shown on the drawing). Notches 18 (FIG. 3) are provided in the eccentric periphery which are associated with the up and down stroke positions. These notches constitute diametrically opposed steps in the eccentric periphery, the base of each one being connected to the top of the other by substantially circular arc portions 21. The notches 18 are on a diameter which passes through the rotational axis of the eccentric as also are the notches 20. However, the diameter of notches 20 is slightly larger than that of notches 18 so that a clearance exists between the eye and the eccentric in the vicinity of their respective notches when the two diameters overlie one another, as is in the case in FIGURE 3. The eye 19 of the connecting plate 6 is of similar shape to the periphery of the eccentric 5. but widened in the shifting direction (that is, generally in the horizontal direction as seen in FIGURE -1) of the connecting plate 6 and is thus provided with diametrically opposed recesses 20 which, in the non-shifting position, are facing at some distance the recesses 18 of the eccentric (FIGURE 3). The difference of size of the eccentric and the eye 19 and the recesses 18, 20 insure that the connecting plate 6, which is compulsorily shifted by the eccentric, will be disengaged from said eccentric in the final up and down stroke positions. In these positions, the connecting plate and eccentric have a clearance of about 1 millimeter between them, while the clearance in the other positions, i.e., the difference between the distance of the tops of the two steps of the eccentric and the distance of the tops of the steps of the eye, is approximately 0.05 millimeter. The connecting plate will be released shortly before the ends of the up and down stroke positions are reached.

FIGURE 4 shows the eccentric immediately before it has reached the end of the shifting movement. The plate 6 is still being shifted at this moment although the speed of the segment 1 is reduced considerably. Only after a slight further circumferential travel of eccentric 5 (about 2 millimeters from the position of FIGURE 4) the plate 6 will become free of the eccentric. FIGURE 3 shows the eccentric slightly more than half a turn later than in FIGURE 4 and in its released position relative to plate 6. It is seen, therefore, that the eccentric 5 ceases to drive the plate 6, and consequently the segment 1, just before the segment reaches its limit or end position relative to the stops 9, 10. The final movement of the segment to complete its stroke is effected by the resilient urging of spring 13. Therefore, the segment 1 reaches its end positions softly and without any jarring halts.

In a known manner, a double-lobed cam disc 22 is arranged axially adjacent the eccentric 5 on the hub of the ratchet wheel 14. The eccentric and disc are rigidly interconnected by a bolt 23. A ratchet pawl 28 is pivoted on pin 29 which in turn extends axially from a radial face of disc 22. The pawl 28 has a tooth end 24 which is adapted to mesh with the teeth on ratchet wheel 14. The pawl is urged to this meshing position by spring 25. An abutment pin 25 extends axially from one face of pawl 28 and is displaced relative to the pivot axis of pin 29. Pin 26 is adapted to alternately abut the hook 30 or the stop surface 31 of the fork lever 27. This lever 27 is actuated by finger key 35 which, when depressed, downwardly pivots the shift case key lever 34 which in turn pivots lever 33 clockwise, which in turn pushes rod 32 to the left and thereby rotates fork lever 27 clockwise against the resilient force of resetting spring 36. The ratchet pawl 28 is kept disengaged from ratchet wheel 14 by virtue of hook 30 on lever 27 abutting pin 26. However, upon lever 27 being rotated clockwise by virtue of key 35 being depressed, hook 30 releases pin 26 whereupon the tooth end 24 of pawl 28 is urged by spring 25 into meshing engagement with a tooth on ratchet wheel 14. Since ratchet wheel 14 is secured to shaft 15 of drive roller 16, wheel 14 rotates continuously with the roller 16. Therefore, when pawl 28 meshes with ratchet wheel 14, the pawl and the cam disc 22 to which the pawl is secured are rotated together with the wheel bolt 26 thereon will abut stop surface 31 on fork lever 27 y and this abutting relationship will pivot pawl. 28 about pin 29 thereby disengaging tooth 24 from the ratchet wheel 14 and further, thereby, discontinuing the driving connection between the ratchet wheel 14 and the eccentric 5. This driving connection is re-established only when the shift key 35 is released (i.e., raised) so that the fork lever 27 rotates counter-clockwise to its position as shown in FIGURE 1. When this occurs, the stop surface moves out of the path of pin 26 so that spring 25 again may push the pawl 28 into meshing engagement with wheel 14. Each half revolution of the eccentric corresponds to an up or down movement of the segment 1. When the disc 22 has rotated another half revolution (i.e., back to the position shown in FIGURE 1), pin 26 will again abut hook end 24 and the driving connection between eccentric 5 and wheel 14 will again be interrupted.

Cam disc 22 has two offset and opposed lobes 37 which follow a spiral rising path and then drop steeply to form steps 38 which are not radial but rather are oblique to the rotational axis of disc 22. The position of these steps is correlated with the up and down shifting positions of eccentric 5. An end of pivoted latch lever 39 is continually urged by spring 39a against the surface of cam disc 22. If one considers, with reference to FIGURE 1, that disc 22 rotates counter-clockwise, it will be seen that as soon as lever 39 begins to slide downwardly along one of the steep outwardly oblique surfaces 38, and since lever 39 is urged downwardly by spring 39a, it will accelerate the rotation of disc 22 until lever 39 reaches the bottom of surface 38 (as is shown in FIGURE 1). This acceleration of disc 22, rotates it slightly counter-clockwise relative to ratchet wheel 14 and thereby separates the tooth 24 from the teeth on the ratchet wheel 14. Since this action coincides with the abutting engagement between pin 26 and either surface 30 or 31, the pawl 28 is easily pivoted out of meshing engagement with wheel 14 without friction occurring between the disengaging parts. Since the force necessary to provide suflicient acceleration of disc 22 is very small, the operation is relatively noiseless and shock-free thereby avoiding wear and tear of the parts.

The segment 1, being urged against one of its stops 11 or 12 by the tumbler spring 13, when, after an action on the key 35 (depression or freeing), eccentric 5 begins to rotate in the direction of the arrows, one curved portion of the eccentric contacts progressively one of the curved portions of the eye 19 and the connecting plate is smoothly urged towards its other position despite the back-lash of the eccentric in the eye because the force of the spring 13 resists the push of the eccentric.

When the dead-point of the tumbler spring 13 is passed, the spring now draws the connecting plate 6.to the other position, but now eccentric having turned about a quarter of a turn in the eye, the back-lash has disappeared and the eccentric compulsorily draws the plate 6 towards the other position. Moreover, as well known, a member conducted by an eccentric moves sinusoidally,

. i.e., the speed of the movement progressively decreases to- 14. Further, since disc 22 is secured by means of pin 23 7 wards the extremities of the limited displacement of said member. (As a matter of fact, the extremities of the displacement, eccentric center, the movement of which is circular, moves perpendicularly to the displacement of the conducted member.)

Consequently, the back-lash having then disappeared (see FIG. 4), the eccentric brakes movement of the connecting plate and segment until arrival of the latter against the further stop; then the connecting plate is freed.

I The lever 39 functions to prevent any clockwise rotation of disc 22 and eccentric 5 after the pawl 28 has been disengaged from wheel 14. As is seen in FIGURE 1, the disc 22 cannot turn clockwise because its step 38 abuts against an end of lever 39'. Therefore, since disc 22 is also prevented from turning counter-clockwise by virtue of pin 26 abutting either surface 30 or 31, and since it cannot rotate clockwise because of lever 39, the disc and eccentric are effectively locked against any rotation while the segment 1 is in its up or down position. The pivot 42 of lever 39 is eccentric so that this pivot may serve to adjust the lever 39 in a clearance-free position with respect to eccentric 5 in normal and shift-over position. A similar eccentric connecting bolt 43 is also provided as a coupling member between the connecting plate 6 and the lever 4 in order to adjust the coincidence of the up and down stroke final positions of the eccentric with the up and down stroke final positions of segment 1 determined by the stops 11, 12. Owing to the back-lash of the connecting plate 6 in the final positions of the eccentric 5 this adjustment requires no excessive exactness and can be performed easily and without much loss in time.

In order to dampen the jerk on the hook end 24 upon engagement, a resilient member and preferably an arcuate flat spring 40 is carried by the clutch pawl. The inturned end of this spring engages with the hook end 24 into the ratchet wheel 14 and said spring is kept by the bolts 26, 41 in such a way that said inturned end slightly protrudes beside the hook end 24. When the clutch pawl 28 is engaged the first drive force caused by the teeth of the ratchet wheel 14 is damped by the blade spring 40, which is then distorted to such an extent that the tooth to be engaged contacts to the hook end 24. The initial acceleration of segment 1 will thereby be reduced which also ensues a decrease in noise and wear and tear.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. In a typewriter, a case shift device comprising a segment shiftable between two stroke positions, tumbler spring means adapted to urge said segment to either of said stroke positions, a continuously rotating drive roller, a shifting means operatively associating said roller to said segment to translate rotary motion of said roller into shifting motion of said segment; said shifting means comprising: a shift plate adapted to oscillate between two opposed shift positions, means connecting said plate to said segment whereby oscillation of said plate effects a shifting of said segment between said stroke positions; said plate having a generally circular eye surrounding an eccentric which is rotatable relative to said plate, means releasably connecting said eccentric to said drive roller, said releasably connecting means comprising a ratchet wheel rotatably driven by said drive roller and a cam disc fixedly attached to said eccentric and rotatable relative to said wheel, a pawl pivotably mounted on said disc between positions of engagement and disengagement with said wheel, resilient means urging said pawl into engagement with said wheel, an abutment pin on said pawl displaced relative to the pivot axis of said pawl, a pivoted fork lever having two opposed stop portions, said fork lever being pivotable into either of two stop positions each of which correspond to a different one of said stop portions being in the rotative path of said abutment pin,

a key shift lever operatively associated with said fork lever to pivot said fork lever to either of said stop posi tions, said eye and said eccentric having generally coincidental respective inner and outer circumferential contours, with the contour of said eccentric sliding against that of said eye as said eccentric rotates, said coincidental contours each being defined by opposed arcs which are offset relative to each other and joined at their offset adoining ends by step portions, said step portions of said eccentric and of said eye lying on respective first and second diameters passing through the axis of rotation of said eccentric, with said second diameter being larger than said first diameter whereby a clearance exists between said eccentric and said eye in the vicinity of their respective step portions when said first and second diameters overlie one another, said second diameter extending generally in the same direction as the direction in which said plate oscillates.

2. The typewriter of claim 1, said cam disc having a circumferential surface defined by two diametrically opposed and offset spiral lobes joined at their offset ends by outwardly oblique steps, a pivoted latch lever resiliently urged against the surface of said cam disc and adapted to abut either of said steps and thereby prevent rotation of said cam disc in one direction.

3. The typewriter of claim 1, wherein the position of said abutment pin on said. pawl is correlated to the direction of said first diameter on said eccentric so that said abutment pin abuts either of said stop portions on said fork lever when said first and second diameters overlie each other said first diameter being in turn correlated to the position of said segment whereby said first and second diameters overlie each other while said segment is approaching either one of said case positions but is still spaced therefrom.

4. The typewriter of claim 2, wherein the position of said abutment pin on said pawl is correlated to the position of said first diameter on said eccentric and to the contour of said cam disc so that said abutment pin abuts either one of said stop portions on said fork lever when said first and second diameters overlie each other and said latch lever begins to slide downwardly on one of said steps when said first and second diameters overlie each other, said first diameter being in turn correlated with the position of said segment whereby said first and second diameters overlie each other while said segment is approaching either one of said stroke positions but is still spaced therefrom.

References Cited by the Examiner UNITED STATES PATENTS 1,827,431 10/1931 Hart l97-7l X 2,275,759 3/ 1942 Helmond 197-74 2,349,723 5/1944 Helmond 19774 2,521,478 9/1950 Petit 19717 2,703,641 3/1955 Yeager 197-74 X 3,071,233 1/ 1963 Chvatlinsky 197-74 ROBERT E. PULFREY, Primary Examiner.

EUGENE R. CAPOZIO, Examiner. 

1. IN A TYPEWRITER, A CASE SHIFT DEVICE COMPRISING A SEGMENT SHIFTABLE BETWEEN TWO STROKE POSITIONS, TUMBLER SPRING MEANS ADAPTED TO URGE SAID SEGMENT TO EITHER OF SAID STROKE POSITIONS, A CONTINUOUSLY ROTATING DRIVE ROLLER, A SHIFTING MEANS OPERATIVELY ASSOCIATING SAID ROLLER TO SAID SEGMENT TO TRANSLATE ROTARY MOTION OF SAID ROLLER INTO SHIFTING MOTION OF SAID SEGMENT; SAID SHIFTING MEANS COMPRISING: A SHIFT PLATE ADAPTED TO OSCILLATE BETWEEN TWO OPPOSED SHIFT POSITIONS, MEAND CONNECTING SAID PLATE TO SAID SEGMENT WHEREBY OSCILLATION OF SAID PLATE EFFECTS A SHIFTING OF SAID SEGMENT BETWEEN SAID STROKE POSITIONS; SAID PLATE HAVING A GENERALLY CIRCULAR EYE SURROUNDING AN ECCENTRIC WHICH IS ROTATABLE RELATIVE TO SAID PLATE, MEANS RELEASABLY CONNECTING SAID ECCENTRIC TO SAID DRIVE ROLLER, SAID RELEASABLY CONNECTING MEANS COMPRISING A RATCHET WHEEL ROTATABLY DRIVEN BY SAID DRIVE ROLLER AND CAM DISC FIXEDLY ATTACHED TO SAID ECCENTRIC AND ROTATABLE RELATIVE TO SAID WHEL, A PAWL PIVOTABLY MOUNTED ON SAID DISC BETWEEN POSITIONS OF ENGAGEMENT AND DISENGAGEMENT WITH SAID WHEEL, RESILIENT MEANS URGING SAID PAWL INTO ENGAGEMENT WITH SAID WHEEL, AN ABUTMENT PIN ON SAID PAWL DISPLACED RELATIVE TO THE PIVOT AXIS OF SAID PAWL, A PIVOTED FORK LEVER HAVING TWO OPPOSED STOP PORTIONS, SAID FORK LEVER BEING PIVOTABLE INTO EITHER OF TWO STOP POSITIONS EACH OF WHICH CORRESPOND TO A DIFFERENT ONE OF SAID STOP PORTIONS BEING IN THE ROTATIVE PATH OF SAID ABUTMENT PIN, A KEY SHIFT LEVER OPERATIVELY ASSOCIATED WITH SAID FORK LEVER TO PIVOT SAID FORK LEVER TO EITHER OF SAID STOP POSITIONS, SAID EYE AND SAID ECCENTRIC HAVING GENERALLY COINCIDENTAL RESPECTIVE INNER AND OUTER CIRCUMFERENTIAL CONTOURS, WITH THE CONTOUR OF SAID ECENTRIC SLIDING AGAINST THAT OF SAID EYE AS SAID ECCENTRIC ROTATES, SAID COINCIDENTAL CONTOURS EACH BEING DEFINED BY OPPOSED ARCS WHICH ARE OFFSET RELATIVE TO EACH OTHER AND JOINED AT THEIR OFFSET ADJOINING ENDS BY STEP PORTIONS, SAID STEP PORTIONS OF SAID ECCENTRIC AND OF SAID EYE LYING ON RESPECTIVE FIRST AND SECOND DIAMETERS PASSING THROUGH THE AXIS OF ROTATION OF SAID ECCENTRIC, WITH SAID SECOND DIAMETER BEING LARGER THAN SAID FIRST DIAMETER WHEREBY A CLEARANCE EXISTS BETWEEN SAID ECCENTRIC AND SAID EYE IN THE VICINITY OF THEIR RESPECTIVE STEP PORTIONS WHEN SAID FIRST AND SECOND DIAMETERS OVERLIE ONE ANOTHER, SAID SECOND DIAMETER EXTENDING GENERALLY IN THE SAME DIRECTION AS THE DIRECTION IN WHICH SAID PLATE OSCILLATES. 